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Signs Your Motorcycle Spark Plugs Have Gone Bad

Posted by Wiley Moody on Feb 10, 2020

mechanic holding a spark plug

Spark plugs are a critical component of the internal combustion engine in motorcycles. Over the years, ignition systems have greatly improved, meaning they don’t demand too much attention. However, motorcycle spark plugs still need to be checked to ensure they’re delivering just the right amount of energy required to ignite the fuel at exactly the right time.

If you’ve owned a motorcycle for some years, you’ve probably dealt with spark plug problems, especially if you own an old motorcycle. Malfunctioning spark plugs could be problematic for your bike. Here are the signs of a bad motorcycle spark plug and wire configuration.

Misfiring Issues

One of the common signs of bad spark plugs is a misfiring engine. This is when you notice that your motorcycle is going off of normal rhythm when running. This often happens for a few seconds, and then the engine gets back to a steady rhythm. Misfiring issues are caused by a damaged motorcycle spark plug that is not arcing at the tip at the right time.

If a spark plug doesn’t arc and give off electricity needed for engine combustion at the right time, it means that the gas it’s supposed to mix with is not where it’s supposed to be so that combustion will be thrown off. When this problem continues, you’ll have difficulties starting your bike until you replace your spark plugs.

Backfiring Issues

Backfiring is also a common sign of bad spark plugs. If you’re hearing random loud pops coming out of your  motorcycle exhaust, then you have a backfiring problem. This is caused by spark plugs that are producing an intermittent spark, which is when a motorcycle spark plug works just fine most of the time but may fail to do so once in a while, causing the engine to backfire.

Whether there's air and fuel in your engine cylinder, if the spark plugs fail to ignite it, it gets pushed out of the engine cylinder on the compression stroke. As soon as it gets to the hot exhaust header, it combusts, causing the loud pop sound.

Flooded Engine

If you’re experiencing engine cranking over and over when starting your motorcycle, then you may have a motorcycle spark plug and wire configuration problem. When this happens, you’ll often have a strong smell of gas. When your engine becomes flooded, it means that the combustion chamber is filling with gas that isn’t being combusted.

Typically, everything else may be working right, including the fuel injector and carburetor that provide the appropriate fuel and air ration. But, if your motorcycle spark plugs are not working right, your motorcycle engine will not start. Get your bike checked by a mechanic to fix the flooding problem.

Strong Smelling Gas or Gas Spraying Out of the Exhaust

When you have malfunctioning spark plugs that aren’t giving a spark at the right time, you’ll have the leftover gas in the engine combustion chamber getting sucked into the engine. Combustion doesn’t happen, so the gas gets past the exhaust valve and shoots out of the motorcycle exhaust pipe.

If you’ve noticed some fluid coming out of your exhaust pipes, confirm that it’s not water caused by condensation. If it’s gas or you’re generally smelling gas when starting your motorcycle, you probably have bad motorcycle spark plugs.

Check the Condition of Your Spark Plugs

spark plug

If you don’t have any of the above issues and are still having problems starting your motorcycle, it’s time to check the condition of your spark plugs. Check for signs like burn marks, a white look, broken or bent parts, or signs of rust and corrosion. Any of these problems can cause spark plug issues. Aging, bad timing on your engine, and running lean may also cause spark plug problems. Inspect your plugs to look out for these signs.

Replace Your Spark Plugs

Motorcycle spark plugs should be replaced every five years. It’s wise to have a look at them before they start causing problems. If you need to replace your  spark plugs and other maintenance parts, get started at West End Motorsports. Spark plugs are easy to install with simple tools. Browse our online store to find more customizable parts and accessories for your motorcycle, including exhausts, fairingswindshieldstiresseatsluggage, and riding gear.

Shop today and enjoy free shipping on orders over $99, plus guaranteed fitment or  contact us now for more information!